Helicopter propeller rotor



FIG. 1 is a perspective side view of a helicopter propeller rotor, showing our new design;

FIG. 2 is an opposite side perspective view thereof;

FIG. 3 is a side view thereof; and,

FIG. 4 is a top view thereof.

The broken lines,shown in the drawings are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a helicopter propeller rotor, as shown and described. 